they had halted for the day, the camp, with its snowy wagon-tilts, its leaping fires, its picturesque backwoodsmen, women, and children, and the oxen browsing or lying down in the sweet thick grass, made a very pretty spectacle.

The Indian still has free range over this delightful plain. The antelope abounds on it; every variety of grouse found in the range is plenty here; deer, bear, and elk are numerous in the fastnesses of the surrounding mountains; and so long as the sun shines warm, no tract can be a better antetype of the Indians' happy hunting-grounds. As if in recognition of this likeness, the tribes had here and there on the plain erected curious mausoleums for their departed braves, consisting of a high pole-staging, upon which the dead lay, wrapped in his blankets in the open air. In no case where we passed these strange monuments were we offended by odors of decomposition. This fact is one of the strongest illustrations of the character of the Rocky Mountain atmosphere, and especially of that part of it which floats dissolved with the purest sunlight over Laramie Plains. The air is different from that on the eastern slope of the Appalachians very much in the same kind that muriatic acid differs from muriate of ammonia. Muriate of ammonia contains acid which has been contains oxygen in its passive state. There are some localities in the mountains where the ozone tests fail of a discovery for months at a time; throughout the mountains, and a distance of many miles eastward on the Plains, iron lies out-of-doors a year at a time without perceptible rusting; such consumptives as come to this region, and settle no higher up the range than they can preserve their ease of respiration, find

satisfied: the air

their disease remarkably retarded. There are several theories looking toward an explanation of the passive oxygen accumulated toward the centre of the Continent. It has been found that the air interpolated between water globules contains a much higher per cent. of active oxygen. The vapor of the sea-board, on its way towards the Rocky Mountains, undergoes progressive condensation upon every eminence, alternating with rarefaction over every heated plain. Both the water that ascends into the higher stratum of clouds to be wafted westward for final condensation on the loftiest snow-peaks of the Rocky range, and that which falls in showers between the Appalachians, or the Gulf margin and the rainless regions of the Platte, contain between their globules a large per cent. of all the ozonized air which they have met in their passage through the atmosphere. Thus in either case, whether the ozone goes entangled with the water into the soil or the supra-human regions of the atmosphere, all the middle space occupied by the range and its neighboring plains has suffered a defiltration of its ozone. If this view of mine be correct, we may naturally look for a powerfully ozonized atmosphere on the highest peaks of the Rocky Mountains. Another theory suggests that the ozone of the sea-board atmosphere is only an allotropic condition of all the oxygen present resulting from the decomposition of sea-water, electrical currents created by the friction of dry and wet air, or from both, and that with the removal of these conditions, as by transportation inland, the oxygen returns to its passive, and, on this hypothesis, its normal state. I prefer the former view, as consistent with the experiments of Schönbein and his theory of the duplex constitution of aërial oxygen by a plus and a minus element.

However we may philosophize about it, the fact is there. All the processes of Nature, which require abundance of active oxygen, are retarded, or even in some cases nearly arrested, in the Plains and the Rocky Mountain region below the snow limits. Tuberculous disease necessitates the oxidation of a larger amount of tissue than the digestion can replace. On reaching Colorado, the patient finds the equilibrium between waste and reparation partially restored, by what we may call the pacification of his inhaled oxygen; the tuberculous deposits are arrested at their present stage, the immature remaining nearly stationary, and the mature cicatrizing after a fashion which sometimes quite surprises the Eastern practitioner. This is not the place to inquire how far the unhealthy products of a strumous diathesis may accumulate elsewhere after they cease to be consumed in the lungs. As it is the oxidation rather than the accumulation which leads directly to a mortal result in such cases, when we have retarded oxidation we have lengthened life. To the consumptive patient, who has a particular interest in living as long as possible, the climate of Colorado offers one of the finest sanitaria in the world. This will be one of the leading advantages of the Territory as soon as our Pacific Railroad has made Denver accessible to invalids. I hope, before many years have elapsed, to see some of the pleasantest sites on the foot-hills between Denver and the Arkansas occupied by institutions for the accommodation and treatment of patients attacked by pulmonary diseases in the East. When the Parks become attainable by any ordinary means of transport, they may form territory for the regeneration of the race in this particular; scrofula dying out of the blood of succes

sive generations reared here, until it shall be impossible to find a baby with the least congenital taint. To be sure, the Indians are decaying away over this identical tract; but their scourge is a worse one than simple scrofula, being none other than scrofula's worst and most invincible parent.

As a mere selfish matter, apart from the obvious humanitarian motives which I never yet found it necessary to urge upon any true member of the noble profession of medicine, I should strongly advise the physician whose studies had been specially directed toward pulmonary disease, if he wished to make himself a name and a fortune, to open a house for the reception of consumptives either at Denver or Colorado City. At the latter spot he might still further enlarge the sphere of his institution, by receiving the classes of patients in whose cases the various Fontaine qui Bouille waters can be employed with benefit.

To return to the Laramie Plains. This vast level has an interest beside its vernal beauty of herbage: its grand entourage of mountains; the exhilarating elixir of its air, which bears infallible evidence of coming fresh from the alembic, virgin from all lungs except one's own; the glorious glimpses of the snowpeaks toward Quien Hornet, and the far ghost of white-robed Laramie. The plain is one of those nodal points in the physical geography of the Continent which must always form the most engrossing objects of research to the catholic student or far-sighted originator of national enterprise. Where man can work with nature, he saves himself an immense deal of drudgery. When he discovers the natural system of communications on a continent, he possesses knowledge of the highest possible use to him in running

his own artificial lines with facility. The study of the natural system leads him directly to the perception of certain nodal points on the earth's surface, to hold which is to hold all the empire between them. Thus, if it be conceivable that any new Alexander should arise to struggle for universal empire, he would practically succeed (in the present state of artificial communication) when he had possessed himself of the Straits of Gibraltar, the Isthmus of Suez, the entrance to the Red Sea, the isthmuses joining North and South America. Similarly the great passes and intra-montane plateaus of the Rocky range involve in their possession the power to dictate to New York and California upon many of their common matters, and the ability at will to unite them by the strongest ties of national cohesion, or eventually break up vital communication between them. The West side of the Continent is overwhelmingly loyal in its animus; proud of the American Union and its own position in it. But the Pacific States will in time grow to be self-sufficient. They will grow, manufacture, import for themselves; and when that maturity arrives, the homogeneity of the two coasts will and should depend upon the degree of facility afforded to intercommunication. So long as it remains a formidable undertaking to pass between New York and San Francisco, so long will there develop an independence of interest and feeling which, however gradual and imperceptible, cannot fail to result in two distinct nations.

The value to the future statesman and engineer of such nodal points as we have mentioned, is well illustrated by a description of the South Pass occurring in ex-Governor Gilpin's interesting book, "The Central